How to make water treatment device hatch?
This is not your final object but it's a way to get the basic shape:


Put your image as a background image.
In Front Ortho, create a plane, rotate it on the X axis, apply rotation, center it, mirror it on X and Z axis to make a symmetrical 2D copy of the blueprint.
Switch to Right Ortho and extrude a bit.
Select some of the vertical bars and extrude again.
Create a UV sphere that follows the shape of the object.
Boolean the 2 objects with the Intersect option.
You have your basic mesh. Dissolve some edges, merge some vertices...
Add some edge loops to sharp the edges. The knife tool will be helpful.